diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 4e5b22b..b36681d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -74,6 +74,30 @@ jobs:
       # feature nothing compiles is a feature that breaks at release time.
       - run: cargo test --tests --features emulation
 
+  # Coverage is additive and NON-REQUIRED: it uploads to Codecov but never
+  # gates a merge (fail_ci_if_error is false, and it is not wired into any
+  # release gate). It mirrors the `test` job's environment — same pinned
+  # toolchain, ubuntu-latest, no `if:` so it runs on every branch and PR just
+  # as `test` does. `--locked` is intentionally omitted to match this crate's
+  # policy (Cargo.lock is gitignored; --locked would fail without it).
+  coverage:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+      - uses: dtolnay/rust-toolchain@1.90.0
+        with:
+          components: llvm-tools-preview
+      - uses: Swatinem/rust-cache@v2
+        with:
+          shared-key: freemkv-unlock-coverage
+      - uses: taiki-e/install-action@cargo-llvm-cov
+      - run: cargo llvm-cov --workspace --lcov --output-path lcov.info
+      - uses: codecov/codecov-action@v5
+        with:
+          files: lcov.info
+          slug: freemkv/freemkv-unlock
+          fail_ci_if_error: false
+
   # The crate ships on macOS and Windows through its consumers, so it has to
   # compile there. Build the tests (not just `cargo check`) — that forces
   # codegen and catches errors in test-only code, which `check` skips.
diff --git a/README.md b/README.md
index cb93b04..cc95989 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,7 @@
 # freemkv-unlock
 
+[![codecov](https://codecov.io/gh/freemkv/freemkv-unlock/branch/dev/graph/badge.svg)](https://codecov.io/gh/freemkv/freemkv-unlock)
+
 The unlock layer for the freemkv toolchain.
 
 An **unlocker removes a drive-level bus-encryption barrier** so the drive serves
diff --git a/codecov.yml b/codecov.yml
new file mode 100644
index 0000000..02c7e1e
--- /dev/null
+++ b/codecov.yml
@@ -0,0 +1,16 @@
+coverage:
+  status:
+    project:
+      default:
+        informational: true
+    patch:
+      default:
+        informational: true
+
+comment: false
+
+ignore:
+  - "tests"
+  - "**/tests"
+  - "benches"
+  - "examples"